I just remembered a little racing game called Revolt. It had the unique ability to drive every single track in mirror, reverse, and mirrored reverse mode.
Now I don't care much for mirror mode, it's a nice addition but unless it barely costs developer time it's not really worth it. But reverse mode... I would love it if every track could be driven the other way around as well. Yes this takes a little bit more thought and care in each track so that you actually can drive every track in both directions (and have enough powerups available in both directions), but once you are done every track counts for 2 while (hopefully) costing less than the time it takes to build 2 tracks.